Resumen

ABSTRACT The detailed sonographic evaluation of the fetal anatomy enables the detection of malformations as well as ultrasound markers of chromosomal defects, specially analyzing the nuchal translucency, which represents the thickness of the sonolucent area located between the skin and the subcutaneous interface of the embryo at cervical level, observed between 11 and 13+6 weeks. It should be used an ultrasound equipment that is able to enlarge the image enough so that the fetus occupies 3/4; of the monitor and allows the differentiation of measurements of up to 0.1 mm, by abdominal or vaginal vias, placing the calipers in an in-in position without mistaking the presence of amnios as an altered measurement. The nuchal translucency acts as the best primary marker in the first trimester of single or multiple pregnancies, of low or high genetic risk, not only to discriminate the chromosomal defects but also for its important association to euploid fetuses with a greater probability of having severe malformations, mostly cardiac. However, the best risk assessment includes the consideration of other factors, including maternal age, family history and biochemical markers.